The present invention relates to not only a method of and an apparatus for visual inspection but also a method of removing the cause of abnormality.
In order to maintain or improve the manufacturing yield and quality of products in the manufacturing process thereof, it is necessary to keep the manufacturing process at a favorable state. When an abnormality is generated in the manufacturing process, it is required to detect the abnormality quickly, to clear up the cause of the abnormality, and to take an appropriate counter-measure. Accordingly, abnormalities in a manufacturing process have been detected as shown in the paper entitled "Knowledge-Based Process Diagnosis Method for Semiconductor Manufacturing" (Transactions of Information Processing Society of Japan) Vol. 27, No. 5, pages 541 to 551) and Japanese patent applications laid-open No. JP-A-60-257,535 and JP-A-62-98,739.
A method of and an apparatus for visual inspection can be used for detecting an abnormality in a manufacturing process. When an abnormality is generated in the manufacturing process, a defect is produced on an object to be inspected, or a foreign particle adheres to the object (such a foreign particle will hereinafter be also referred to as a "defect"). Thus, the appearance of the to-be-inspected object is varied. That is, the abnormality in the manufacturing process can be detected by inspecting the appearance of the object.
According to a method of and an apparatus for visual inspection, however, actual defects do not always exist on a one-to-one basis for detected defects. Accordingly, it has been impossible to accurately judge an abnormality in the manufacturing process, and to remove the cause of abnormality surely. Thus, it has been impossible to maintain or improve the manufacturing yield and quality of an article.